One of the methods for exposing a photographic material is concerned with a known method for forming an image by a so-called scanner system in which an original is scanned and a silver halide photographic material is exposed to light stemming from the image signal to form a negative or positive image equivalent to the image of the original.
There are various recording devices to which the method for forming an image by the scanner system is practically adopted. A glow lamp, a xenon lamp, a mercury lamp, a tungsten lamp, a light emitting diode, and others have hitherto been used as the sources of light for the recording devices of the scanner system. However, from a practical viewpoint, all these sources have the disadvantage of low output and short life. To overcome these drawbacks, coherent laser sources such as a Ne-He laser, an argon laser and a He--Cd laser have also been used as sources for the scanner system. Although high output is obtained from these sources, the devices equipped with them have the disadvantage of being large-sized and expensive and, in addition, need a modulator.
On the other hand, semiconductor lasers are small-sized, inexpensive, readily modulated, and have longer life than that of the above-mentioned lasers. In addition, because the semiconductor lasers emit light in the infrared region, a photosensitive material having sensitivity in the infrared region can be advantageously treated under a bright safe light so that operating efficiency of handling can be improved.
Photosensitive materials to which the semiconductor lasers having such advantages can be applied are commercially available in recent years, and further photosensitive materials having superhigh contrast come to be desired.
Photographic materials comprising silver halide grains containing silver chloride which have sensitivity to light emitted by the semiconductor lasers and, that is, are spectrally sensitized in the infrared region are described in JP-A-60-80841 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-62-299838, JP-A-62-299839, JP-A-61-70550, JP-A-63-115159, JP-A-63-115160, and JP-A-63-115161.
Photographic materials of a silver bromide or silver iodobromide type are described in JP-A-63-49752, JP-A-63-83719 and JP-A-63-89838.
To improve the sensitivity in the infrared region, a number of sensitizing dyes have been hitherto developed, in addition to the sensitizing dyes described in the above-mentioned patent specifications. These sensitizing dyes are described in U.S. Pat. Nos. 2,095,854, 2,095,856, 2,955,939, 3,458,318, 3,482,978, 3,552,974, 3,573,921, 3,582,344, 3,615,632, and 4,011,083.
A system in which superhigh contrast can be achieved by adding a hydrazine compound to an emulsion spectrally sensitized in the infrared region is known and described in JP-A-64-26841, JP-A-2-35443, JP-A-2-184841, and JP-A-2-113238. The photographic materials described in these patent specifications, which can be treated with developers of pH 11.0 or less, are liable to cause fogging and black peppers.
In the system for which hydrazines are used, photographic materials containing silver chlorobromide which is subjected to chemical sensitization are disclosed in JP-A-53-20921, JP-A-60-83028, JP-A-60-140399, JP-A-63-46437, JP-A-63-103230, JP-A-3-294844, JP-A-3-294845, JP-A-4-174424, JP-A-6-19035, and so forth. Further, photographic materials in which a silver halide emulsion contains a hydrazine compound together with a heavy metal complex such as rhodium and iridium are described in JP-A-60-83028, JP-A-61-47942, JP-A-61-47943, JP-A-61-29837, JP-A-62-201233, JP-A-62-235947, JP-A-63-103232, and so forth.
On the other hand, in the developers for photographic materials in the field of graphic arts, dihydroxybenzenes are used as a developing agent. Although hydroquinone is mostly used among the dihyroxybenzenes, the use of hydroquinone as the developing agent has seemed to have some disadvantages from the ecological and toxicological viewpoint in recent years.
Endiols such as ascorbic acid are known to function as a developing agent and attention is paid to the fact that they have no ecological and toxicological problems. For example, U.S. Pat. Nos. 2,688,549 and 3,826,654 have disclosed that a developer containing an endiol can form an image under a highly alkaline condition of pH 12 or higher at least. Further, the endiols are described in U.S. Pat. Nos. 5,236,816 and 5,098,819 from the viewpoint of developing agents that have no ecological and toxicological problems.